Voltage regulating system



July 4, 1939. c. HANNA ET AL y 2,165,049

VOLTAGE REGULATING SYSTEM Filed Jan. 16, 1937 2 Sheets-Sheet 2 WlTN ESSES: INVENTOR 5. 7),/ .z I, (ZIN/0f? @Hanna f and KS//Ap nger 5M y Patented July 4, 1939 UNITED STATES VOLTAGE REGULATING SYSTEM Clinton R.. Hanna, Pittsburgh, and Kirk A. 0p-

linger, Verona, Pa., assignors to Westinghouse Electric & Manufactum: Company,

Pittsburgh, Pa., vania East a corporation of Pennsyl- `.Application January Y16, 1937, Serial-No. .120,914

9 Claims. (Cl. 171-119) 'Our invention relates to regulator systems and" December 31, 1936, and assigned to the same particularly to such systems that are adapted for maintaining constant an electric quantity, such as voltage.

When a vibrating regulator is used to control an exciter generator for supplying excitation to the main generator to maintain the voltage of the circuit supplied thereby constant, the voltages V of the main and exciter generators usually becomes unstable and start hunting alternately above and lbelow the desired value when Aan attempt is made to improve the regulation of th generator beyond a certain point.

Manyvanti-hunting devices have been provided for regulators to reduce such hunting. Such devices, in general, provide a. damping action which slows down the rate of response ofthe regulator, or introduces a counter force into the regulator of such a nature as to interrupt the regulator action temporarily, thereby reducing its sensitivity.

It is an object of our invention to provide a regulator system that is highly sensitive and quickly responsive to.changes in the regulated D quantity from the desired value, and that introduced into the regulator action based on the ratesV ci response of the several units. Other objects and advantages of our invention will be apparent from the following description of certain illustratedembodiments thereof, reference being had to the accompanying drawings, in

which: f

Figure 1 is an elevational view of a regulator that is suitable for employment in the system of assignee as thisapplication. The regulator comprises a supporting panel I upon which are suitably mounted stationary contact members 2 and 3 and a core structure 4 of magnetic material having a winding leg for accommodating an energizing winding 5 and providing a space in the magnetic structure for accommodating an armature 6 attached to a lever 1 that is pivotally mounted to the core structure by means of fiat horizontal and vertical springs 8 and 9, respectively, and that carries, at its upper end, a movable contact mem-- ber I2 that is adapted to engage the contact members I and 2. The lever 1 is biased by a spring I4 about a pivot axis I3 formed along the line of intersection of the planes of the horizontal springs and vertical springs 8 and 9, respectively. One

other end of the spring I4 being attached to a stud I6 carried by a bracket I1 mounted on the panel I.

Referring to Fig. 2, a main generator I8 isQprovided having a eid Winding I9 and an armature winding 22 that is connected to line conductors 23 and 24 to supply alternating currentthereto. A full waveretier 25 is provided, the alternating current terminals of which are connected between conductors 23 and 24 and the direct current terminals of which are connected by conductors 26 and 21 to the regulator winding 5. A condenser 28 or other means may be connected for ltering any alternating current vibrations' from the circuit of conductors 26 and 21.

An exciter gnerator 32 is provided having a ileld winding 33 and an armature winding 34,

`the armature winding being connected by conductors 35 and 36 for energizing the field winding I6 of the main generator I8. Qne terminal 31 of the eld winding 33 is connected to conductor 35 and t'o regulator contact member 2 by conductor38, the other terminal 39 being connected to the movable regulator contact member I2 through resistor 42to conductor 36. A feedback or anti-hunting transformer 43 is provided having a primary Winding 44 that is connected to be energized in accordance with the voltage applied across the generator eld winding I2, and a secondary Winding 45 that is connected in the circuit between the rectifier 25 and the regulator winding 5.

:When the generator and exciter voltages are constant, direct current ows in thev primary winding 44 of the transformer 43 so that no current isinduced in the secondary winding 35 thereof and the energization of the winding 5 is determined solely by the voltage applied thereto from conductors 2 3 and 24.

With the field resistor 42 shunted from the circuit of the exciter eld winding 33 by engagement of the regulator contact members l2 and 3, as illustrated, the voltage of the exciter will build up causing the voltage of the main generator I8 to also increase until the pull on the winding 5 is sufficient to move the regulator lever arm I in a counterclockwise direction to separate the contact members I2 and 3 and to insert the resistor 42 in series with the exciter generator eld Winding 33, thus causing the voltage of the exciter generator and of the main generator to decrease. Upon .this decrease in voltage, the decrease'in energization of 4the regulator winding 5 also decreases so that the pull of the spring I4 becomes greater than the magnetic pull of the core 4, thus permitting the lever 'I to move in a clockwise direction to again cause engagement of the contact members I2 and 3 to again shunt the resistor 42 from the-circuit of the exciter generator winding 33. The alternate engagement and separation of the contact members I 2 and 3 take place very rapidly because of the high sensitivity of the regulator thus preventing wide departures in the regulator voltage from its desired value.

So long as the voltage impressed across the eld winding I9 of the main generator I8 is constant, a unidirectional current of constant value will flow in the primary winding 44 of the transformer 43 and consequently no voltage will be induced thereby in the secondary winding 45. Upon a change in the voltage of the generator I8 from its desired value, the initial change in energization of the winding 5 is, therefore, solely determined by the voltage between conductors 23 and 24 which causes a movement of the regulator arm I in a direction to correct for departure of the generator voltage from its desired value. This correction causes a change in the voltage of the exciter generator 32, and va corresponding change in the voltage impressed across vthe primary winding 44 of the transformer 43, the rate of change of which determines the amount of voltage introduced in the secondary winding 45. The winding 45 is so connected in the circuit of the regulator winding 5 that a feedback voltage is introduced into the circuit thereof in a direction opposite to the change in voltage causing the regulator action. If, for example, the voltage of the generator I8 drops, the voltage across the regulator winding 5 correspondingly drops thus "causing the regulator to effect an increase in the output voltage of the exciter generator 32 to thereby increase the output voltage of the main generator I 8. The rate of change of the output voltage of the exciter generator 32 introduces into the winding 45 a voltage in a direction to increase the energizetion of the winding 5 and thereby cause separation of the contact members I2 and 3 sooner than would be effected were the winding SenergizedY solely in accordance with the voltage impressed on conductors 26 and 2'I from the rectifier 25. The feedback voltage applied to the winding 5 through the transformer 43 is thus am'easure of the rate of build-up in the voltage across the main generator field I3 and anticipates the rate of recovery of the regulated quantity to its desired Value,'thus introducing into the regulator circuit a component of voltage to interrupt the main regulator action suiliciently before complete arcane correction to prevent an excessive build-up in the voltage of the main generator beyond its desired value. Upon an increase in voltage across the conductors 23 and 24 above the desired value, the initial action of the regulator causes a decrease in the excitation of the exciter generator 32 and the main generator I8. The decrease in the output voltage of exciter generator 32 causes a change in current flow through the primary Winding 44 of the transformer 43 which induces a feedback voltage in the winding 45 in a direction to decrease the energization of the winding 5 below the value of voltage supplied from the rectifier 25, thus permitting an earlier engagement of the contact members I2 and 3 to prevent the excitation of the exciter generator 32 and of the main generator I8 from decreasing suiciently that the voltage across conductors 23 and 24.drops excessively below the desired value `It will be appreciated that the contact member I2 engages and separates from engagement with the contact member 3 at a rapid rate so that, in effect, these contact membersconstitute a 'varying resistor which increases in value as the percentage of time that the contact member I2 is separated from engagement with the contact member 3 increases, and decreases in value as the percentage of time that the contact Vmember I2 is in engagement with the contact member 3 increases. y

Should the residual voltage of the exciter generator 32 become so high that the excitation of the field winding 33 required to maintain the desired voltage between conductors 23 and 24 is less `than that which would be maintained if Y the resistor 42 were continuously in series with the field winding 33, the regulator will so operate that the contact member I2 vibrates into and out of engagement with the contact member 2 instead of with the contact member 3. l

'Ihe embodiment of the invention illustrated in Fig. 3 is similar in fundamental operative char# acteristics `to that illustrated in Fig. 2, the main generator 46 beingshown as having a direct current armature winding 41 connected to circuit conductors 48 andI 49. The regulator control circuit conductors 26 and 21y may, therefore, be directly connected to conductors 48 and 43 without the necessity of providing the rectifier 25 shown in Fig. 2. Also, in the embodiment illustrated in Fig. 3, a-winding 52 that'is inductively coupled to the field winding 33 of the exciter generator 32 is connected in circuit with the winding 5 to introduce the feedback voltage into the regulator circuit. The'voltage induced in the winding 52 will be proportional to the rate of change of current in the eld winding 33 and in a direction determined by the direction of current change.

A feedback voltage may be introduced into the circuit ofthe regulator winding 5 by means of a current transformer 53, as illustrated in Fig. 4, the secondary winding 54 thereof producing a current that is proportional to the rate of current change in the circuit of the main generator field winding I9,4 and the direction of which is dependent upon whether such eld excitation current increases or decreases.v In Fig. 4 also the eld winding 33 of the exciter generator 32 is shown as being separately excited from conductors 55 and 56 if the regulation is controlled by cooperation between contact members I2 and 3 to provide one .direction of energization of the 'leld winding 33, the eld winding being energized from conductors-55 and 51 when the regulator action is effected 'through cooperation of t.

contact members 2 and 2 to provide a reverse J direction of energization of the field winding 88.

In Fig. 5, another embodiment of the invention is illustrated employing a direct current main generator 48, and in which the primary winding 44 of the feedback transformer 48 is directly connected across conductors 48 and 49 that are connected to the armature winding 4 1 of the main generator".y This arrangement provides the same character o f regulation as when the primary winding 44 is connected across the output circuit of the exciter generator, asin Fig. 2, but requires a larger feedback transformer 48 to produce a corresponding feedback voltage since the time element of the machine 48 causes a slower change in the voltage across the l. conductors 48 and 49 than that which takes place between conductors 85 and 88 in response to a regulator action and therefore a flower voltage per turn in the winding 44.

In Fig. 6, a plurality of exciter generators 92, 89 and 84 are shown connected in cascade, each providing the source of energization of the field winding of the next machine for energizing the main generator 85 which supplies current to conductors 96 and 81, the voltage of which it is desired to maintain constant. Consequently, a full wave reactor 68 is connected between conductors 88V and 81 for providing unidirectional voltage to the regulator winding 5 that is proportional to the alternating voltage between conductors 89 and 61. The direct current exciter generator 62 1 comprises a self-excitedfleld winding 69 and an armature winding 12 that supplies current to the field winding 13 of the exciter generator 93 andv is provided, with an armature winding 14 for supplying current to the eld winding 15 of vexciter generator 84, and which is provided with an armature winding 15 that, in turnfsupplies current to the field winding 11 of the main generator 85, the armature winding 18 of which supplies alternating current to the conductors 68 and 81.

Feedback transformers 82, 8 3 and 84 are provided, the primary winding of transformer 82 being connected across the armature winding 12 of exciter generator 82, the primary winding 81 of feedback transforxnerr 83 being connected across armature winding 14 of 'exciter generator 88, and the primary winding 89 of the transformer 84 being connected across the armature winding 18 of exciter generator 84. The secondary windings 88, 8f and 92 of the feedback transformers 82, 88 and 84, respectively, are fconnected in series with the regulator winding 5 to introduce into the circuit thereof feedback voltages similar in direction to those discussed with respect to the previously described' figures but which are responsive to the rate of change of the voltages of the three cascaded exciter generators 92, 98 and 84, respectively.

It will be appreciated that any number of exciter generators may beconnected in cascade, as illustrated in Fig. 6, but three will ordinarily be all that is required to provide excitation for the largest generator employed today with a field current of approximately one-fourth ampere being required for the first exciter generator of the series. 'I'hus the regulator contact members will be required to control current of the order of one-fourth ampere in order to amplify the output currents of the several exciters to a value sufficient to provide complete excitation for they generator 85. Since the machines increase ,incise from the'first orsmallest exciter 82 to the main generator 88, the time constants of the field windings of these machines correspondingly increase, so that the feedback voltage introduced into the regulator winding circuit through transformer 82 precedes the introduction of the feedback voltage introduced through transformers 83 and 84, and the feedback voltage introduced by transformer 81 is initiated before that 4produced by transformer 84, the several feedback voltages. 4being additiva to give complete anti-hunting ac,

tion 'as the effect of the regulator action is felt on the main machine 85. Thus a very rapid and very accurate .degree of anti-hunting or feedback current is introduced into the regulator winding so that machines so controlled may be governed by very sensitive and quick acting regulators without producing hunting action resulting from the cascading of machines In Fig. F6, the feedback vtransformers 82, 88 and 84 are connected as shown in Figs. 2 and 5, but it will be appreciated that the particular means of introducing feedback current into the regulator winding circuit illustrated in Figs. 3 and 4 may be employed if desired. It will be appreciated that the series of cascade connected exciter generators constitute amplification devices for amplifying a relatively small corrective stimulus that is .determined in part by variations in the regulated quantity and in part by the rate of response of the several generators lor some of them to the influence of the-corrective impulse:

It will be appreciated that since the time constants of the field windings of the machines 92;

83 and 64 expressed as where L is the inductance and`R the resistance of the winding increase in series, because of the increased sizes of the machines in the cascade connection. constantsf the various feedback transformers expressed as y where M is the mutual inductance between the windings and R is the resistance of the primary winding are related to the electrical characteristics of the fields across which they are connected. For stability purposes, thatis to prevent hunting, the time constant y of a feedback'transformer must :be equal to or greater than the time constat of the field damper har or pole eddy current. For reasonably good damping of 60% decay per cycle of free voltage oscillations might be about one-tenth the time constant of thev main field winding. Ina machine where for the main nem' winding is 1o`seconds a time constant for the feedback transformer of one second is very satisfactory. This gives a time con- It has 'been found that the time,

stam that is ten times that of the damper bar/ and one-tenth that of the main field winding.

The secondary winding @2 of Itransformer 84 may Vbe connected in circuit with the regulator Winding 5, as shown in Fig. 7, the primary Winding 89 being connected in series with the secondary winding 36 of the transformer 82 and with the secondary winding B8 of the transformer 83. This reduces the resistance of the transformer windings in series with the winding `5, thus reducing the error that might result from failure of voltage changes on the winding 5 following closely the changes in the output voltage of the rectier 68.

It will be apparent to those skilled in the art that modifications may be made in the apparatus and circuits illustrated Without departing from the spirit of our invention, -We do not Wish to be limited-otherwise than by the scope of the appended claims.

WeL claim as our invention:

1. In a regulatorsystem, a plurality of electric generators having field windings and arranged in series so that the output from .one generator is employed to energize the field winding of the next generator in the series, means for controlling the excitation of said generators comprising a regulator having a. winding and means including a circuit for energizing said Winding in accordance with a voltage that is a measure of a `regulated electrical quantity controlled by said generators, and means for introducing into said circuit stabilizing impulses proportional to thev rates of change in the excitation of said several generators. f

2. In a regulator system, a pilot element responsive to variations in a quantity to be regulated for controlling a relatively small corrective stimulus determined in part by said variations, a plurality of ,amplification devices connected in cascade for. amplifying the effect of said corrective stimulus, and means for inuencing said pilot element also in response to the rates of change of the out-puts ,of more than one of said amplification devices.

3. In a generator voltage regulator system, a pilot element responsive in part to variations in a regulated voltage from its desired value, means governed by said pilot element for controlling a relatively small corrective stimulus determined by said variations, a plurality of exciter generators connected in cascade for amplifying said corrective stimulus, and means for causing said pilot element to be responsive also to the rate ofl change of the output of one or more of said exciter generators.

4. In a regulator system, aV regulating relay responsive to variations in a regulated quantity, means governed by said relay for controlling a small corrective stimulus determined in part by variations in the regulated quantity, a plurality of. exciter generators connected in\cascade for amplifying said corrective stimulus, and means for introducing into the circuit of said regulating relay stabilizing voltages determined Vby the rates of change in the output voltages of a plurality of said exciter generators.

5. In a regulator system, a regulator relay having a Winding and circuit,J therefor, means for applying a voltage to said circuit thatnis a measure of the regulated quantity, a plurality of exciter generators connected in cascade and serially gov- ,erators erned by said relay, and means comprising feedback transformers associated with `said several exciter generators for introducing stabilizing voltages into the circuit of said relay Winding that are determined by the rates of change in output voltages of said several exciter generators.

6. In a regulator system, an electric generator having a field winding, an exciter generator for energizing the field winding of said first named generator, means for controlling the excitation oi' said exciter generator comprising a regulator having a Winding and a circuit for energizing said Winding at a voltage that is a measure of 'a regulated electrical quantity controlled by said first named generator, and means for introducing into the circuit of the regulator winding stabilizing voltage components that are counter to the change in energization of said regulator Winding and proportional respectively to the ratesof change in excitation of said two gen- 7. In a regulator system, an' electric generator having a field Winding, an exciter generator for energizing said field winding, means for controlling the excitation of said exciter generator comprising a regulator having a winding and a circuit for energizing said winding in accord-l ance with the voltage that is a measure of the regulated quantity controlled by said first named generator, and means comprising a plurality of feedback transformers responsive to the respective rates of change in excitation of said several generators, the several feedback transformers being designed to have time constants that are predetermined fractions of the time constants ofy their associated generators.

8. In a regulator system, a regulating relay responsive to variations in a regulated quantity, a plurality of amplification devices connected in `series and having serially increasing time constants, means governed by said relay for develop- 1 ing a small corrective stimulus on the first of said amplification devices that is determined in part by variations in the regulated quantity and in,

part by the rates of response of the several amplication devices to the influence of the `corrective impulse, the time constants of the means for determining the part responsive to the rates of response of the several amplification devices having propressively increasing time constants that are less than the time constants of their associated amplification devices.

9. In a regulator system, a regulator relay having a winding and circuit therefor, means for applying a voltage to said circuit that is a measure of the regulated quantity, na. plurality of exciter generators connected in cascade and serially governed by said relay, said several exciter generators having progressively larger time constants than the preceding generator in the series, and means comprising feedback transformers associated with said serially connected exciter generators for introducing stabilizing voltages into the circuit of said relay winding that are determined by the rates of change in excitation of the several exciter generators, said several feedback transformers having time constants less than the time constants of their associated exciter generators.

l'CLINTON R. HANNA. KIRK A. oPLINc-ER. 

